Apart from the technical challenge, is there any reason why these side sticks could not be arranged to move together?
Remember the current flight control interface in the airbii is basically a 70ies design. The technology for backdriven cross controlled sidesticks was available, but deemed too complicated. It was feared that they introduce too many other failure modes which had to have been dealt with. In that light, the software dealing with the force feedback on the 777 consisted supposedly of more lines of codes than the whole airbus FBW system.